Make eye contact with the people passing, nod to them, gesture keen interest in talking to them at a later time, point to your phone, shrug and move on.

与经过的人进行眼神交流，向他们点头，做出很感兴趣且稍后会与他们交谈的手势，指向你的手机，耸耸肩，然后继续前行。